.file "libm_frexp_4f.s"

// Copyright (C) 2000, 2001, Intel Corporation

// All rights reserved.

//

// Contributed 2/2/2000 by John Harrison, Ted Kubaska, Bob Norin, Shane Story,

// and Ping Tak Peter Tang of the Computational Software Lab, Intel Corporation.

//

// Redistribution and use in source and binary forms, with or without

// modification, are permitted provided that the following conditions are

// met:

//

// * Redistributions of source code must retain the above copyright

// notice, this list of conditions and the following disclaimer.

//

// * Redistributions in binary form must reproduce the above copyright

// notice, this list of conditions and the following disclaimer in the

// documentation and/or other materials provided with the distribution.

//

// * The name of Intel Corporation may not be used to endorse or promote

// products derived from this software without specific prior written

// permission.

//

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL INTEL OR ITS

// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY

// OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY OR TORT (INCLUDING

// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

//

// Intel Corporation is the author of this code, and requests that all

// problem reports or change requests be submitted to it directly at

// http://developer.intel.com/opensource.

//

// History

//==============================================================

// 2/02/00: Initial version

// 3/20/00: Improved speed

// 6/01/00: Fixed bug when x a double-extended denormal

// 12/08/00 Corrected label on .endp

//

// API

//==============================================================

// float frexp(float x, int* y)

// float __libm_frexp_4f(float x, int* y)

//   where int* y is a 32-bit integer

//

// Overview of operation

//==============================================================

// break a floating point x number into fraction and an exponent

// The fraction is returned as a float

// The exponent is returned as an integer pointed to by y

//    This is a true (not a biased exponent) but 0fffe is subtracted

//    as a bias instead of 0xffff. This is because the fraction returned

//    is between 0.5 and 1.0, not the expected IEEE range.

//

// The fraction is 0.5 <= fraction < 1.0

//

// Registers used

//==============================================================

// general registers:

// r14  exponent bias for x negative

// r15  exponent bias for x positive

// r16  signexp of x

// r17  exponent mask

// r18  exponent of x

// r19  exponent result

// r20  signexp of 2^64

// r32  on input contains the 32-bit IEEE float that is in f8

// r33  on input pointer to 32-bit integer for exponent

// predicate registers:

// p6   set if x is Nan, zero, or infinity

// p7   set if x negative

// p8   set if x positive

// p9   set if x double-extended denormal

// floating-point registers:

// f8  input, output

// f9  normalized x

// f10 signexp for significand result for x positive

// f11 signexp for significand result for x negative

// f12 2^64

#include "libm_support.h"

.align 32

.global __libm_frexp_4f#

.section .text

.proc  __libm_frexp_4f#

.align 32

__libm_frexp_4f:

// Set signexp for significand result for x>0

// If x is a NaN, zero, or infinity, return it.

// Put 0 in the int pointer.

// x NAN, ZERO, INFINITY?

// Set signexp for significand result for x<0

{ .mfi

(p0)    mov         r15 = 0x0fffe

(p0)    fclass.m.unc p6,p0 = f8, 0xe7

(p0)    mov         r14 = 0x2fffe

}

// Form signexp of 2^64 in case x double-extended denormal

// Save the normalized value of input in f9

// The normalization also sets fault flags and takes faults if necessary

{ .mfi

(p0)    mov         r20 = 0x1003f

(p0)    fnorm       f9 = f8

        nop.i 999 ;;

}

// Move signexp for significand result for x>0 to FP reg

// Form 2^64 in case x double-extended denormal

{ .mmi

(p0)    setf.exp    f10 = r15

(p0)    setf.exp    f12 = r20

        nop.i 999 ;;

}

// Move signexp for significand result for x<0 to FP reg

// If x NAN, ZERO, INFINITY, set *y=0 as a 32-bit integer, and exit

{ .mmb

(p0)    setf.exp    f11 = r14

(p6)    st4         [r33] = r0

(p6)    br.ret.spnt b0 ;;

}

// Form exponent mask

// p7 if x<0, else p8

{ .mfi

(p0)    mov         r17 = 0x1ffff

(p0)    fcmp.lt.unc p7,p8 = f8,f0

        nop.i 999 ;;

}

// Test for fnorm(x) denormal, means x double-extended denormal

{ .mfi

        nop.m 999

(p0)    fclass.m.unc p9,p0 = f9, 0x0b

        nop.i 999 ;;

}

// If x double-extended denormal add 64 to exponent bias for scaling

// If x double-extended denormal multiply x * 2^64 which is normal

{ .mfi

(p9)    add         r15 = 64, r15

(p9)    fmpy        f9 = f9, f12

        nop.i 999 ;;

}

// true exponent stored to int pointer

// the bias is treated as 0xfffe instead of

// normal 0xffff because we want the significand

// to be in the range <=0.5 sig < 1.0

// Store the value of the exponent at the pointer in r33

// If x>0 form significand result

{ .mfi

        nop.m 999

(p8)    fmerge.se   f8 = f10,f9

        nop.i 999  ;;

}

// Get signexp of normalized x

// If x<0 form significand result

{ .mfi

(p0)    getf.exp    r16 = f9

(p7)    fmerge.se   f8 = f11,f9

        nop.i 999  ;;

}

// Get exp of normalized x

// Subtract off bias to get true exponent of x

{ .mmi

(p0)    and         r18 = r17,r16 ;;

(p0)    sub         r19 = r18,r15

        nop.i 999  ;;

}

// Store int y as a 32-bit integer

// Make the value a float

{ .mfb

(p0)    st4         [r33] = r19

(p0)    fnorm.s     f8 = f8

(p0)    br.ret.sptk b0 ;;

}

.endp __libm_frexp_4f

ASM_SIZE_DIRECTIVE(__libm_frexp_4f)

strong_alias(__libm_frexp_4f, _GI___libm_frexp_4f)